During the four coming weeks, best experts in bitumen will bring you their knowledge and experience to build a strong understanding of today’s realities and new perspectives on the future of bitumen.
Total is the European leader on bitumen markets. Innovation has always been the key to sustainability and durability in the products they develop. Their main objective here is to share technical knowledge and experience to insure bitumen are being used in the most effective and efficient ways for their different applications in road works.
Ecole des Ponts, France oldest engineering school, remains very much in the present, as it has always been, in training engineers in order to meet the needs of our society and citizens in key areas such as transport housing and urban services, but also in fields like energy, environment, climate sciences, land-use planning and sustainable development.
Nineteen world recognized experts on bitumen are contributing to this MOOC.
The idea is to provide the broadest prism on this topic area with speakers coming from research, industry and end users.

Nadège VO VINH

Cécile GIACOBI

Laurence LAPALU

Yves BROSSEAUD

Emmanuel CHAILLEUX

Research Director

Jean-François CORTE

Member of the Council of Environment and Sustainable Development

Transcription

[MUSIC] Hello, my name is Gilles Gauthier. I'm responsible for the technical coordination and product development at Total Bitumen. Let's start with the modification of bitumen with polymers. In this video you will find information about the different types of polymers that can be used and the benefits of polymer modification. Polymer modified bitumen called PMB, generally consists of a blend of a bitumen with a polymer. Polymers are large molecules composed of the addition of many small molecules called monomers into a chain. Two different types of monomers can be combined into a single polymer, which is then called a copolymer. The most common type of polymer used to modify bitumen is a copolymer of polystyrene and polybutadiene. It is usually called SB or SBS. This family of copolymers is called an elastomer because it brings viscosity and elasticity to the bitumen. More than 80% of the polymer used in bitumen are SB or SBSs. But there's another type of polymer that can be used in the bitumen modification. It is a copolymer of polyethylene and polyesters like, for instance, phenyl acetate. This family of copolymer is called plastomers because it brings stiffness and plasticity to the bitumen. There are many different grades of SBS and plastomers that are suitable for bitumen modification. They differ by their properties like, for instance, molecular size, ratio between copolymers, molecular structure. These parameters impact the mechanical properties of the polymer and therefore the properties it will bring to the polymer modified bitumen. Now let's focus of the main properties brought by the polymer modification of bitumen. Polymer modification stiffens the bitumen at elevated surface temperatures, say, around 50 to 70 degrees. Therefore, PMBs have higher ringable temperature and are less sensitive to creep. The resulting asphalt mix will have an improved resistance to rutting or permanent deformation. Also, at very low temperatures PMBs are less stiff and more flexible than regular bitumen. They have a lower fast point and a higher toughness. It makes polymer modified asphalt mixes more resistant to thermal cracking. In other words, PMBs are less sensitive to extreme temperatures. They can be used on a wider range of temperature compared to regular bitumen. Polymer modification improves binder cohesion. At low and intermediate temperature, bitumen may be too brittle. Under traffic, the film of bitumen holding the aggregates together may break, causing the aggregates to come off. This phenomenon is called raveling. PMBs have increased cohesion energy. It requires much more energy to break because of their high elasticity or plasticity. As a consequence, the asphalt mix will be much less sensitive to raveling. SBS modified bitumen are typically more viscous than regular bitumen. This may become a problem if the viscosity is too high, because the product can no longer pumped or it will not coat the aggregates properly, or the asphalt mix can no longer be fully compacted. On the other hand, plastomer modified bitumen are much less viscous. Polymer modification improves the binder resistance to aging. Bitumen on the road is subjected to aggressive climatic conditions like oxidation by air, UV light, water, changes in temperatures. All of these combine with traffic loads. Over time, bitumen tends to stiffen and become more brittle. In the case of PMB, the aging phenomenon is mitigated, which brings some extra durability to the pavement. Finally, polymer modification improves the resistance to fatigue. Fatigue is the development of cracks by the repetition of loading cycles. It is responsible for the failure of many pavements. PMBs are more resistant to fatigue. They develop damage at a slower pace, bringing extended lifestaying to the pavement. Now you know about the main properties of PMBs. We will now see more specific PMB technologies also available on the market. The first one is crosslink PMBs. The crosslinking technology is based on the modification of the polymer structure in the bitumen matrix by adding a crosslinking agent, creating bonds between the polymer chains. The outcome is a complete change in the PMB's microstructure, becoming completely homogeneous. This technology has been patented by Total in 1978 and is widely renowned under the brand name Styrelf, with 300,000 tons sold each year by Total and its licensees over the world. As a consequence, the PMB receives additional outstanding properties of elasticity, resistance to fatigue, raveling, and temperature susceptibility. PMBs are essentially a suspension of swollen polymer particles inside a bitumen's matrix. This suspension is not always stable, and in some cases the polymer tends to separate from the bitumen within a few hours. It is then necessary to stir such blends continuously to ensure proper homogeneity. On the other hand, crosslinked PMBs are naturally stable for months. Another technology is offered by reactive terpolymers. Some advanced plastomers are available on the market. These polymers are modified with a special chemical containing an epoxy component. This plastomer is more stable than bitumen, and brings higher elasticity and extra stiffness to the PMB. Now let's summarize what we have learned about polymer modified bitumen. Polymers used to modify bitumen are either elastomers, typically SBS polymers, or plastomers, typically polyethylene copolymers. PMBs have improved mechanical properties compared to regular bitumen. These properties include lower temperature susceptibility, resistance to fatigue, lower aging, and high cohesion. Finally, cross linking allows further improvement of the performance of SBS modified bitumen. I thank you for your attention. [MUSIC]